Many industries, such as the chemical and pharmaceutical industries, require mixing of substances (e.g., chemicals) in extremely clean environments. In order to meet the requirements of these industries, specially-designed mixing tanks and stirring mechanisms have been developed.
Substances in many of the above-mentioned tanks are discharged from the tanks by being allowed to flow through openings located at or near the bottom of the tanks. Therefore, in order to promote homogeneity of the flows coming out of the tanks, the stirring mechanisms are typically located at the bottom of the tanks.
One currently-available stirring mechanism has a first portion thereof (i.e., an exterior portion) configured to be positioned on the outside of a tank and a second portion (i.e., an interior portion) configured to be positioned on the inside of the tank. Each of the interior portion and the exterior portion have magnets included therein.
The interior portion includes a cavity and, when positioned inside of the tank, the cavity accommodates the insertion therein of a raised feature on the bottom surface of the tank. Because the thickness of the tank is substantially uniform, the raised feature inside of the tank has an associated indentation on the outside of the tank. When the indentation has dimensions that allow for the interior portion to be inserted into the indentation, the interior portion may be magnetically coupled to the exterior portion through the tank wall at the location of the indentation.
In operation, once the exterior portion is positioned in the indentation and the raised feature is inserted into the cavity of the interior portion, the exterior portion is rotated about a fixed axis by a motor and a set of gears that are positioned outside of the tank and that are connected to the exterior portion. Because of the magnetic coupling between the interior portion and the exterior portion, as the exterior portion is rotated, the interior portion, which has a set of blades attached thereto, is also rotated. As the interior portion and blades are rotated, the set of blades agitates and/or mixes the substances at the bottom of the tank and a degree of homogeneity is achieved locally at the bottom of the tank.
Because the blades are positioned adjacent to the bottom of the tank, very little fluid flow is possible between the blades and the bottom of the tank. In other words, very little exhaust flow is possible below the bottom of the blades. Therefore, the above-discussed mixing tank is only relatively successful at homogenizing substances at the bottom of a tank.
In addition to the above, because the blades are positioned adjacent to the bottom of the tank, substances at the top of the tank are oftentimes too far away from the blades to be substantially agitated or mixed by the blades. Therefore, the likelihood of achieving a homogeneous mixture throughout the tank using the above-discussed mixing tank is even further reduced. At least in view of the above factors, the composition of substances flowing out of the tank when the tank is relatively full may differ from the composition of substances flowing out of the tank when the tank is relatively empty due, which is an undesirable condition.
Also, the presence of an indentation at the bottom of the tank and the need to position the second portion relative to the indentation makes insertion of the stirring mechanism relatively difficult, particularly in relatively tall tanks. Further, the presence of the indentation makes the tank more difficult to clean than smooth-bottomed tanks.
Accordingly, there is a need in the art to provide an apparatus and method for mixing, agitating or stirring substances that are configured to promote substantial homogeneity throughout a tank. Further, there is a need in the art for such mixing, agitating or stirring apparatuses that may be more easily inserted and removed from a tank, so that the tank may be easily cleaned. Even further, there is a need in the art to provide a mixing apparatus and method for mixing substances that minimize friction and wear, thereby reducing the amount of particulates that get released into a tank during mixing.